Convergence units for color television picture tubes

ABSTRACT

Generally U-shaped cores are employed, each having a pair of legs and an intermediate portion extending between the legs. The intermediate portion may be either solid or formed with a gap. A reduced number of coils is employed on each core. In each case, there is only one vertical convergence coil, and either one or two horizontal coils. The vertical coil may be mounted on the intermediate portion, or on one of the legs. The horizontal coil or coils may be mounted on one or both legs.

United StatesPatent Anthony et al.

541 CONVERGENCE UNITS roR COLOR TELEVISION PICTURE TUBES [72] Inventors: Albert M. Anthony, Conneaut; Richard .1.

Anthony, Ashtabula, both of Ohio [73] Assignee: Tracor, lnc., Austin, Tex.

'[22] Filed: July 16, 1970 [211 Appl. No.: 55,387

52] U.S.Cl ass/210313777 51 Int.Cl.

[58] FieldofSearch .......335/210,2l3;313/75,77; 315/2-7 [56] References Cited UNITED STATES PATENTS 3,325,675 6/1967 Sanford ..313/75.x

on 3,657,675 [451 Apr. 18,1972

2,864,021 12/1958 Lazzery ..335/210X 3,002,120 9/1961 Clay ..313/77 Primary Examiner-George Harris Attorney-Burmeister, Palmatier & Hamby ABSTRACT Generally U-shaped cores are employed, each having a pair of legs and an intermediate portion extending between the legs. The intermediate portion may be either solid or formed with a gap. A reduced number of coils is employed on each core. In each case, there is only one vertical convergence coil, and either one or two horizontal coils. The vertical coil may be mounted on the intermediate portion, or on one of the legs. The horizontal coil or coils may be mounted on one or both legs.

14 Claims, 7 Drawing Figures Patented April 18,1972 3,657,675

- z Sheets-Sheet 2 4 Patented April 18, 1972 3,557,675

3 Sheets-Sheet :3

CONVERGENCE UNITS FOR COLOR TELEVISION PICTURE TUBES This invention relates to convergence units adapted to be mounted around the neck of a color television cathode ray picture tube. Such a picture tube has three electron guns in spaced relation to the axis of the tube. The beam of each gun is directed to illuminate phosphor dots of a certain color on the screen of the tube. The phosphor dots are usually arranged in arrays for each color. The electron beam from each gun passes through an aperture screen or shadow mask which as a single set of holes in the same geometric configuration as each array of dots. When the electron beam travels its intended course, it illuminates only those dots which produce the intended color. The electron beams from all three guns are aimed to converge upon the holes in the mask, and thereafter the beams diverge as they pass through the holes and arrive at the screen as three individual beams.

By means of static convergence adjustments, the beams may be aimed to converge at the center of the mask, but problems arise when the beams are swept from side to side and up and down. The convergent point of the beams sweeps in an arc which moves it away from the mask at points other than the center of the mask. Convergence coil assemblies or units have been devised and are used to meet this problem. The beams must converge on the mask so that all three beams pass through the same hole in the mask at correct angles to strike the corresponding phosphor dots on the screen. These assemblies are known as dynamic convergence units because they correct any variations in the length from the deflection point to the apertured mask, as the beams are deflected from the center to the edges of the mask.

Prior convergence units have generally utilized a plurality of U-shaped cores having legs with convergence coils mounted thereon. It has been the practice to mount one horizontal convergence coil and one vertical convergence coil on each leg, so that each core is equipped with two horizontal and two vertical convergence coils. The coils are energized with horizontal and vertical convergence signals developed by special circuits in the television set. These signals are effective to maintain the convergence of the three beams as they are deflected both horizontally and vertically from the center of the mask.

One type of convergence unit utilizes three cores and three sets of coils thereon, spaced at equal angular intervals around the axis of the tube so as to be opposite the three electron beams. Another type of convergence unit utilizes only two cores with two sets of coils thereon, disposed at diametrically opposite points. One core and the coils thereon provide the convergence correction for one electron beam, generally the blue beam. The other core and the coils thereon provide the convergence correction for the other two beams, generally the red and green beams.

One of the principal objects of the present invention is to provide a new and improved convergence unit in which the number of coils is greatly reduced, while preserving the ability of the unit to provide the necessary dynamic convergence corrections.

In accordance with the present invention, it has been found that each core of a triple core convergence unit may be provided with only one vertical convergence coil and either one or two horizontal convergence coils. These coils areenergized with the usual horizontal and vertical signals. One horizontal coil and one vertical convergence coil may be mounted on either the same leg or different legsof the U-shapedcore. Alternatively, the vertical coil may be mounted on the intermediate portion of the core, extending-between the two legs. In that case, it is preferred to provide a fully balanced construction by mounting interconnected horizontal coils on both legs. In either case, the core may be of the type in which the intermediate portion is interrupted by a gap. An adjustable permanent magnet is mounted across this gap to provide an initial biasing flux. Alternatively, the core may be of the solid type, without any such gap.

In the double core type of convergence unit, one core may unit, with only one vertical coil, and either one or two interconnected horizontal coils. The other core of the double-core convergence unit has one vertical coil and two horizontal coils, mounted on the two legs. The vertical coil may be mounted on the intermediate portion, or on one leg.

The construction of the present invention greatly reduces the cost and complexity of the dynamic convergence units. Nevertheless, it has been found that the convergence units are fully capable of providing the necessary convergence corrections.

Further objects, advantages and features of the present invention will appear from the following description taken with the accompanying drawings, in which:

FIG. 1 is a diagrammatic sectional view of a triple-core convergence unit to be described as an illustrative embodiment of the present invention.

FIGS. 2, 3 and 4 are fragmentary sections showing modified constructions.

FIG. 5 is a diagrammatic section showing a double-core type of convergence unit, constituting another illustrative embodirnent of the present invention.

FIGS. 6 and 7 are diagrammatic elevational views showing other modified constructions.

It will be seen that FIG. 1 illustrates a triple-core type of dynamic convergence unit 10 adapted to be mounted around the neck 12 of a color television picture tube. The convergence unit or assembly 10 comprises three convergence devices 14, one for each of the electron beams, designated B, R and G for blue, red and green. It will be understood that suitable means are provided to mount the convergence devices 14 around the neck 12 of the picture tube, at substantially equal angular intervals. Those skilled in the art will be familiar with such mounting means, which are not illustrated in the diagrammatic representation of FIG. 1.

In this case, all of the dynamic convergence devices 14 are the same in construction. Each device 14 comprises a U- shaped core 16 having a pair of legs 18 and an intermediate or connecting portion 20, extending between the outer ends of the legs. The core 16 is made of a suitable magnetic material, such as a ferrite material. As shown, pole pieces or shoes 22 are mounted against the inner ends of the legs 18. The pole pieces 22 are immediately adjacent to the neck 12 of the picture tube.

In the illustrated core 16 the connecting portion 20 is interrupted by a gap 24. Tape or other thin non-magnetic material 26 may be mounted in the gap 24. An adjustable permanent magnet 28 is mounted on the connecting portion 20 so as to extend across the gap 24. The illustrated magnet is of the disc type, which may be rotated to change the initial or biasing magnetic flux in the core.

In accordance with the present invention, each core 16 is provided with only one horizontal convergence coil 30, and only one vertical convergence coil 32. These coils are supplied with suitable horizontal and vertical convergence signals by the convergence circuits in the television receiver. It has been the prior practice to provide two horizontal and two vertical convergence coils on each core, one horizontal coil and one vertical coil having been mounted on each leg of the core. However, it has been found that one horizontal convergence coil and one vertical convergence coil may be eliminated, so

that only one coil of each kind is utilized on the core. This construction will provide the necessary horizontal and vertical convergence corrections.

The horizontal and vertical convergence coils 30 and 32 may be mounted on the same leg, or on different legs. In the construction of'FIG. l, the coils 30 and 32 are mounted on different legs. It will be understood that either coil may be mounted on either leg.

FIGS-3 and 4 illustrate modified constructions in which the horizontal and vertical convergence coils 30 and 32 are mounted on thesame leg. In this case, the horizontal coil 30is mounted within the hollow space 34 formed in the vertical coil 32. In this way, both of'the coils 30 and 32 may be positioned be the same as used for the three-core type of convergence near thepole pieces 22.

In the construction of FIG. 1, the vertical convergence coil 32 is formed with the hollow space 34, but the space is left unoccupied. FIG. 2 illustrates a modified construction utilizing a vertical convergence coil 32a which does not have such a hollow space. Vertical coils of either type may be employed as desired.

The modified construction of FIG. 2 also utilizes a modified core 160 having a connecting portion 20a which is solid, rather than being formed with a gap. Either type of core may be employed as desired.

The modified construction of FIG. 3 utilizes the same core 16 as in FIG. 1. However, the horizontal and vertical coils 30 and 32 are on the same leg of the core, rather than being on different legs. It will be understood that the coils 30 and 32 may be mounted on either leg.

The modified construction of FIG. 4 is the same as that shown in FIG. 3, except that the construction of FIG. 4 utilizes the solid core 16a, of the type shown in FIG. 2.

FIG. 5 illustrates a convergence unit or assembly 40 which is of the type which utilizes only two convergence devices, mounted at diametrically opposite positions around the neck 12 of the color TV picture tube. One convergence device is the same as illustrated in FIG. 1 and is designated 14, as in FIG. 1. All of the components of the convergence device are also identified by the same reference characters.

Convergence unit 40 of FIG. 5 utilizes a second convergence device 42 which is the same as the convergence device 14 except that the convergence device 42 has two horizontal convergence coils 30, one such coil being mounted on each leg 18 of the core 16. Thus, one horizontal convergence coil is used to provide the correction for the red beam, while the other horizontal coil is employed to provide the correction for the green beam. The single vertical convergence coil 32 provides the vertical convergence correction for both beams. It will be understood that the vertical coil 32 may be mounted on either leg 18 of the core 16.

As before, the cores of FIG. 5 may be formed with or without the gap 24. In the case of convergence device 14, the horizontal and vertical convergence coils 30 and 32 may be mounted on the same leg, or on different legs. Either coil may be mounted on either leg. 1

FIG. 6 illustrates another modified convergence device 114 having a U-shaped core 116 which is the same as the core 16a in FIG. 2. Thus, the core 116 has a pair of legs 118 and a solid intermediate or connecting portion 120. It will be understood that the intermediate portion 120 may be provided with a gap, if desired.

The convergence device 114 is provided with two horizontal convergence coils 130, and a single vertical convergence coil 132. The horizontal coils 130 are symmetrically mounted on the legs 118, while the vertical coil 132 is mounted on the intermediate portion 120 of the core 116. This arrangement provides a balanced construction which is highly adventageous. The convergence device 114 of FIG. 6 can readily be used as a direct replacement for existing types of convergence devices, without any change in the electronic circuits for developing the horizontal and vertical direction signals.

The convergence device 114 of FIG. 6 has the further advantage that it can be used in either a triple core unit, similar to that of FIG. 1 or a double core unit, of the type illustrated in FIG. 5. For use in a triple core unit, the horizontal convergence coils 130 are normally interconnected to receive the same horizontal correction signal. This is also true when the convergence device 114 is used as the blue beam convergence device for a double core unit, of the type shown in FIG. 5. When the convergence device 114 is used for the red and green beams, the horizontal convergence coils 130 are connected to different circuits, to receive the horizontal correction signals for the red and green beams.

FIG. 7 illustrates still another modified convergence device 214, which is the same as the device of FIG. 6, except that the core 116 of FIG. 6 is replace by a modified core 216 having generally radial legs 218 and an intermediate portion 220 of increased length. Thus, the core 216 is basically U-shaped and is generally in the form of a triangle. The legs 2l8extend generally in radial directions relative to the axis of the television picture tube.

The horizontal and vertical convergence coils and 132 are the same as before. Thus, the horizontal coils 130 are mounted on both legs 218, while the vertical coil 132 is mounted on the intermediate portion 220, to provide a balanced construction. Instead of being solid, as illustrated, the intermediate portion 220 may be formed with a gap, if desired.

Certain features of the convergence device with the triangular core are covered in the co-pending Pat. application of Albert M. Anthony, Ser. No. 46,311 filed: June 15, 1970, and entitled Convergence Unit for Color Television Picture Tube. The convergence device 214 of FIG. 7 has all of the advantages of a symmetrical or balanced construction as discussed in connection with FIG. 6.

It will be evident that the present invention makes it possible to reduce the number of coils employed in the convergence unit. Thus, the cost and complexity of the convergence unit are greatly reduced. Nevertheless, it has been found that the convergence units of the present invention are fully capable of providing the necessary dynamic convergence corrections.

Various other modifications, alternative constructions and equivalents may be employed, as will be evident to those skilled in the art.

We claim:

1. A convergence unit construction, comprising a horseshoe-type core having a single magnetic circuit including a pair of legs and an intermediate connecting portion extending between said legs at one end thereof,

a single vertical convergence coil mounted around said intermediate connecting portion of said core,

and a pair of horizontal convergence coils mounted around said respective legs of said core,

said core having a single magnetic axis extending along said legs and said intermediate connecting portion,

all of said coils encircling said single magnetic axis of said core.

2. A construction according to claim 1, in which said core is generally U-shaped.

3. A construction according to claim I, in which said core is generally triangular in shape.

4. A convergence unit construction,

comprising a horseshoe-type core having a single magnetic circuit including a pair of legs and an intermediate connecting portion extending between said legs at one end thereof,

a single vertical convergence coil mounted around said core,

and at least one horizontal convergence coil mounted around one of the legs of said core,

said vertical convergence coil being substantially larger than said horizontal convergence coil.

5. A construction according to claim 4,

in which said vertical convergence coil is mounted around said intermediate connecting portion of said core.

6. A construction according to claim 4,

in which only a single horizontal convergence coil is provided and is mounted aground a leg of saidcore.

7. A construction according to claim 6,

in which said horizontal coil and said vertical coil are mounted around the same leg of said core.

8. A construction according to claim 6,

in which said horizontal coil and said vertical coil are mounted around different legs of said core.

9. A construction according to claim 4,

in which said portion of said core extending between said legs is interrupted by a gap.

10. A construction according to claim 4,

in which said portion extending between said legs of said core is solid.

11. A construction according to claim 4,

coil and at least one such horizontal convergence coil.

14. A construction according to claim 4,

including a second such core spaced diametrically opposite said first mentioned core,

said second core having a pair of such legs and an intermediate portion extending between said legs,

first and second such horizontal convergence coils mounted around different legs of said second core,

and a single such vertical convergence coil mounted around said second core. 

1. A convergence unit construction, comprising a horseshoe-type core having a single magnetic circuit including a pair of legs and an intermediate connecting portion extending between said legs at one end thereof, a single vertical convergence coil mounted around said intermediate connecting portion of said core, and a pair of horizontal convergence coils mounted around said respective legs of said core, said core having a single magnetic axis extending along said legs and said intermediate connecting portion, all of said coils encircling said single magnetic axis of said core.
 2. A construction according to claim 1, in which said core is generally U-shaped.
 3. A construction according to claim 1, in which said core is generally triangular in shape.
 4. A convergence unit construction, comprising a horseshoe-type core hAving a single magnetic circuit including a pair of legs and an intermediate connecting portion extending between said legs at one end thereof, a single vertical convergence coil mounted around said core, and at least one horizontal convergence coil mounted around one of the legs of said core, said vertical convergence coil being substantially larger than said horizontal convergence coil.
 5. A construction according to claim 4, in which said vertical convergence coil is mounted around said intermediate connecting portion of said core.
 6. A construction according to claim 4, in which only a single horizontal convergence coil is provided and is mounted around a leg of said core.
 7. A construction according to claim 6, in which said horizontal coil and said vertical coil are mounted around the same leg of said core.
 8. A construction according to claim 6, in which said horizontal coil and said vertical coil are mounted around different legs of said core.
 9. A construction according to claim 4, in which said portion of said core extending between said legs is interrupted by a gap.
 10. A construction according to claim 4, in which said portion extending between said legs of said core is solid.
 11. A construction according to claim 4, in which two such horizontal convergence coils are mounted around the respective legs of said core.
 12. A construction according to claim 11, in which said vertical convergence coil and one of said horizontal convergence coils are amounted around the same leg of said core, the other horizontal convergence coil being mounted around the other leg.
 13. A construction according to claim 4, including three such cores spaced around a circle at substantially equal angular intervals, each of said cores having a single such vertical convergence coil and at least one such horizontal convergence coil.
 14. A construction according to claim 4, including a second such core spaced diametrically opposite said first mentioned core, said second core having a pair of such legs and an intermediate portion extending between said legs, first and second such horizontal convergence coils mounted around different legs of said second core, and a single such vertical convergence coil mounted around said second core. 